My mom is a poly artist and does use anything on her pieces, that shine like nothing I have seen beore. She buffs/sands a TON though. and I mean her stuff SHINES. when she first started working she used future flor polish, but now would rather sta ynatural.

There are a number of acrylic finishes that can be used to give polymer clay a sheen, right on up to a high-glossy shine. Most clayers tend to use either Varathane or Future though because they both work well (though a bit differently) and are dead cheap. The Fimo folks put out the very best finish as one of their 4 versions (it's actually alcohol- based), but it's really-really expensive for the amount you get. Other liquids can be used too like 2-part epoxy resin, thinned white glues, etc., but again, Varathane and Future are the most common.

A sheen, right on up to a high gloss can also be given to baked polymer clay by wet-sanding then buffing it after baking (buffing by hand will give only a sheen, but buffing by some kind of machine can take it all the way up). Some clayers even elect to do both, especially for the glossy finishes ... sanding/buffing and also using a liquid finish, sometimes in layers.

Btw, the brand of polymer clay called Kato Polyclay bakes up with a natural sheen because of its density... Sculpey bakes up the most matte... Premo, the 2 Fimos, and Cernit are in-between.

If you want to read about all the different clear finishes that can be used on polymer clay, when they're actually needed, and the differences between brands, ways to apply, etc., check out this page at my site:http://www.glassattic.com/polymer/finishes.htm